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Influence of Equatorial CH⋅⋅⋅O Interactions on Secondary Kinetic Isotope Effects for Methyl Transfer
Author(s) -
Wilson Philippe B.,
Williams Ian H.
Publication year - 2016
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201511708
Subject(s) - kinetic isotope effect , chemistry , kinetic energy , isotope , hydrogen bond , molecule , catechol , methyltransferase , photochemistry , deuterium , computational chemistry , stereochemistry , organic chemistry , methylation , biochemistry , atomic physics , physics , quantum mechanics , gene
DFT calculations for methyl cation complexed within a constrained cage of water molecules permit the controlled manipulation of the “axial” donor/acceptor distance and the “equatorial” distance to hydrogen‐bond acceptors. The kinetic isotope effect k (CH 3 )/ k (CT 3 ) for methyl transfer within a cage with a short axial distance becomes less inverse for shorter equatorial C⋅⋅⋅O distances: a decrease of 0.5 Å results in a 3 % increase at 298 K. Kinetic isotope effects in AdoMet‐dependent methyltransferases may be m∧odulated by CH⋅⋅⋅O hydrogen bonding, and factors other than axial compression may contribute, at least partially, to recently reported isotope‐effect variations for catechol‐ O ‐methyltransferase and its mutant structures.